A multi-source electrical power system can include an electrical bus that can receive power from multiple power sources. For instance, contactors or other switching elements can be used to selectively couple each of the multiple power sources to the electrical bus. At least one of the power sources coupled to the electrical bus can include a power converter used to convert the power generated by a power source to a power suitable for the electrical bus.
For instance, in an aviation system, electrical power for avionics, motors, and other electrical equipment on an aircraft can be provided by multiple generator systems coupled to the electrical bus. Each generator system can include a generator coupled to a gas turbine engine. Each generator can convert mechanical energy generated by the gas turbine engine to alternating current (AC) power. A power converter can be used to convert the generated AC power to a direct current (DC) power for a DC electrical bus.
It can be desirable in certain circumstances to switch power delivery between power sources coupled to the electrical bus. For instance, it may be desirable to transfer power delivery from one of the multiple power sources to another power source. Transferring power delivery between power sources coupled to the electrical bus can lead to power interruptions and/or disturbances in power quality, such as voltage dips or voltage spikes or high circulating current between the related sources.
For instance, in AC systems, power delivery transfer among multiple power sources in a multi-source electrical power system can be achieved by setting a voltage of a pickup source (e.g., the power source that is being added to the electrical bus) to a voltage that is higher than a voltage of the power source already delivering power to the electrical bus. This can result in power oscillations between the power sources because the higher voltage setpoint of the new power source can result in picking up the entire load on the electrical bus. This can potentially cause a drop in bus voltage as current increases and the load shifts back to the original source. In addition, the frequency of the source being connected to the bus can be slightly offset from the frequency of the bus. As a result, unknown and uncontrolled load shifting between sources can occur when the new source is added to the electrical bus.
In DC systems, a pickup source can be coupled to the electrical bus using power sources capable of sourcing or sinking loads up to and including the full power capability of each of the sources. In addition and/or in the alternative, complex algorithms can be used to adjust internal voltage setpoints among regulators for the power sources to reduce circulating current. These techniques can result in unknown and uncontrolled load shifts and can result in significant oscillations between power sources and large power losses.
Thus a need exists for systems and methods for transferring power delivery among power sources in a multi-source electrical power system while reducing power interruptions and disturbances in power quality.